Beginner's Guide — Post Only Orders

Post Only orders are an advanced limit order type that allows users to "only be makers." When the Post Only mode is selected, the limit orders submitted by users will not immediately match and execute against existing market orders. If the system determines that a Post Only order would immediately match and execute against existing market orders, the system will automatically cancel that order.

Advantages of Post Only

The Post Only mode ensures that when users place limit orders, they will not be executed immediately (i.e., they will not become takers). Instead, it guarantees that they always act as makers, providing liquidity to the market. As a result, when the order is filled, users can enjoy the maker fee rate discount and will not be charged the taker fee by the system.

For example, during highly volatile market conditions, the BTC price has dropped to 10,005 USDT. If you want to buy 10 BTC at a price of 10,000 USDT and place an order, but the market price continues to fall quickly and BTC soon reaches 9,995 USDT.

Scenario One

If you did not set the Post Only mode, when the BTC price rapidly falls to 9,995 USDT, your order to buy 10 BTC at 10,000 USDT will immediately match and execute against existing market orders. At this point, your role will change to taker, and you will pay the taker fee for this transaction (which is higher than the maker fee). Additionally, you will not be able to buy BTC at a better price.

Scenario Two

If you set the Post Only mode, when the BTC price rapidly falls to 9,995 USDT, the system will determine that your order to buy 10 BTC at 10,000 USDT would immediately match and execute against existing market orders, so the order will be canceled. In this case, you will not pay any additional taker fees for this order, and you will have the opportunity to adjust your strategy to buy BTC at a better price.

In summary, for quantitative trading institutions with specific strategies and exchange market makers, the Post Only mode allows them to always act as liquidity providers, saving significant amounts in trading fees. This mode offers a clear trading advantage compared to other order strategies. At the same time, for "sniping traders," in highly volatile markets, the Post Only mode not only avoids additional trading costs caused by rapid executions but also gives traders the chance to readjust their trading strategies to achieve greater profits.